1. Field of the Invention
This invention relates generally to environmental protection aids and more particularly to a spill containment device for the fill tubes of storage tanks, particularly underground storage tanks, for environmentally hazardous liquids such as gasoline and other petroleum products.
2. Discussion of the Prior Art
As will appear from the ensuing description, the present spill containment invention may be utilized on virtually any liquid storage tank having a fill tube through which thetank is filled. The invention may also be used on both above ground and below ground storage tanks. However, the invention is particularly concerned with underground storage tanks for petroleum products, such as gasoline, diesel fuel and the like.
Underground storage tanks used in the storage of toxic or flammable liquids, such as those used for storage of petroleum products at service stations and the like, normally include a casing or fill pipe that runs from the subsurface tank up to the ground surface. A manhole surrounds the upper end of the casing in order to access the casing and provide clearance for a valve used to connect delivery truck fill hoses to the casing. Although most liquid product delivery trucks or equipped with a shut-off valve that stops liquid flow to the fill hose when a storage tank is full, spillage of product is common when filling such tanks. Spills normally occur due to leakage at the fill pipe-hose coupling or by the discharge of the standing liquid within the truck hose. Even though the truck's shut-off valve halts delivery to the base, the truck hose remains filled with liquid product. When the hose is disconnected from the casing, this remaining liquid runs out onto the ground.
The contamination produced by such liquid storage tank spills results in a substantial health hazard. When toxic or flammable liquids, such as gasoline, diesel fuel or the like are dumped onto the ground, these products may enter the local ground water or otherwise enter into the ecosystem. Even if the spillage is not absorbed into the ground but is drained off into a sewage system, a toxic or explosive atmosphere can be produced within the local sewer system.